Piezo inhaler

ABSTRACT

An inhaler provides a controlled delivery of an inhalant and includes an inhaler housing and a mouthpiece coupled to the inhaler housing. A piezoelectric dispenser-head is coupled to the inhaler housing and configured to be coupled to the dispensing chamber. The piezoelectric dispenser-head includes an array of dispensing channels and an array of dispensing nozzles. The array of dispensing channels are formed with actuatable walls made at least partially of a piezoelectric material. Application of an electric field to selected side walls reduces a volume in an associated channel and creates a pressure pulse of flowable substance in the associated channel through a dispensing nozzle.

RELATED APPLICATIONS

This patent application is a continuation of and claims priority fromU.S. patent application Ser. No. 09/256,144, filed on Feb. 24, 1999, andentitled “Piezo Inhaler,” now U.S. Pat. No. 6,196,218 which issued onMar. 6, 2001, the entire disclosure of which is incorporated in itsentirety herein, and further claims priority from: 1) U.S. patentapplication Ser. No. 08/578,707, filed on Dec. 28, 1995, and entitled“Dispenser,” now U.S. Pat. No. 5,894,841 which issued on Apr. 20, 1999;2) PCT Application No. PCT/AU94/00355, filed on Jun. 28, 1994, andentitled “Dispenser,” now abandoned; 3) Australian Patent ApplicationNo. PM1709, filed Oct. 8, 1993; 4) Australian Patent Application No.PM0925, filed Aug. 31, 1993; 6) Australian Patent Application No.PL9769, filed Jul. 2, 1993; and 5) Australian Patent Application No.PL9673, filed Jun. 29, 1993.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an inhaler, more particularly to an inhalerwith a piezoelectric dispenser-head.

2. Description of Related Art

There are currently three main methods for drug delivery via therespiratory tract, namely metered dose inhalers, dry powder inhalers,and nebulizers.

Metered dose inhalers (“MDI”) are widely used in the management ofasthma. The MDI comprises a drug packaged with a propellant in apressurized aerosol container can having a valve which releases avolumetric metered dose of aerosol upon actuation. These inhalers areportable, small, and convenient to carry but deliver a dose which variesin quantity, delivery speed, and droplet size distribution as the vaporpressure of the propellant varies. The propellant pressure varies withtemperature and decreases progressively as the content becomes depletedso that the range in dose variation may be substantial. Incompleteevaporation of the propellant may cause “sticking” and localizedconcentration of drug droplets at an impact area, and this in turn cancause undesirable side effects. For example bronchosteroids can causelocal immuno-suppression and local fungal infection while localconcentration of bronchodilator can lead to swallowing, with unwantedsystemic affects. In addition, the use of an MDI requires a degree ofsynchronization between manual valve actuation and inhalation which manyusers find difficult.

Dry powder inhalers (“DPI”) devices rely upon a burst of inspired air tofluidize and draw a dose of an active powder into the bronchial tract.While this avoids the synchronization problem of the MDI, DPI's aresensitive to humidity and may provoke asthma attacks in some individualssensitive to inhaled powder. Moreover, because the force of inspirationvaries from person to person, the dose administered varies.

Nebulizers generate an aerosol by atomizing a liquid in a carrier gasstream and require a continuous gas compressor or bulky supply ofcompressed gas. In general, the droplet size of the aerosol is afunction of carrier gas pressure and velocity and hence cannot be easilyvaried independently of concentration of the active substance in the gasstream. Inhalation reduces the pressure at the nebulizer nozzle and thusdosage and particle size are also influenced by the duration andstrength of each breath. Most nebulizers operate continuously duringinhalation and exhalation but special control systems can be employed tometer the aerosolized gas flow from the nebulizer to a holding chamberfrom which the user may draw a charge.

In general the precision of dose delivery of each of these devices isless accurate than desirable and restricts their use to drugs which havebroad dosage tolerance. In each case delivery of the active agent to theintended application site is overly dependent on user technique and isvariable from dose to dose and person to person. Not only is an improveddelivery system required to optimize current nasal and pulmonarytherapies utilizing locally acting drugs but there has long beenrecognized a potential for the administration of many additional localand systemic drugs if a more satisfactory means of delivery wereavailable. Medical advances suggest that pulmonary delivery of drugssuch as peptides, proteins and analgesics might be of considerableadvantage compared with conventional oral or injection delivery means.For example it has been suggested that insulin for diabetics may bedelivered via the pulmonary route if a suitable means of delivery wereavailable. The deposition of drug particles on lung tissue is a functionof size, shape and density of particles or droplets. For many drugs,control of one or more of these factors along with precise dose or doserate control would be desirable. However, at the present time no meansof drug delivery is available which adequately meets such requirements.

Many attempts have been made to provide a cigarette substitute whichprovides nicotine by inhalation but which avoids the need for combustionof tobacco. Provision of a cigarette substitute involves complexitiesadditional to those involved in the administration of a therapeuticagent. Although it is relatively easy to administer nicotine (forexample in tablet form, via transdermal patches and the like), suchforms do not satisfy habitual smokers because they do not satisfyimportant complex physiological and psychological affinities acquired byhabitual smokers of combustible cigarettes.

In an attempt to provide an acceptable alternative, many cigarettesubstitutes have been proposed which provide nicotine on inhalationwithout combustion of tobacco. Conceptually, such devices are lessharmful to the inhaler than smoking, avoiding the hazards of; passivesmoking among bystanders, and the fire hazard and environmental problemsassociated with cigarette smoking. However, despite these majoradvantages, no device so far proposed has met with consumer acceptance.

Early cigarette substitutes employed a porous carrier impregnated with aliquid nicotine containing composition through which an air stream couldbe drawn to volatilize nicotine. This approach yielded insufficientnicotine per puff, suffered from a tendency for the carrier to dry outand delivered a variable amount of nicotine per puff, depending onfactors such as air temperature, humidity, lung capacity of the user andamount of liquid composition remaining in the carrier.

Subsequent devices delivered nicotine from a pressurized aerosolcontainer from which nicotine can be released by mechanical valveactuator. In one such device the valve is microprocessor controlled tolimit the frequency and duration of actuation. However, the dosedelivered varies with the vapor pressure of aerosol remaining in thecontainer as well as with duration of valve actuation. The disposablepressure container, aerosol valve, and CFC propellant add considerablyto active substance cost. These devices share the disadvantages of MDIdevices previously discussed.

In yet other devices a nicotine containing substance is heated tovaporize an amount of nicotine which is then available for inhalation.The amount of nicotine delivered by such devices is difficult to controland is temperature dependant. In one such device a plurality ofnicotine-containing pellets may be heated sequentially so that eachliberates a predetermined dose. However, in that case, the dose is fixedduring pellet manufacture, particle size of the aerosol is uncontrolled,and temperature of the inhaled air cannot be varied independently ofdose.

Factors such as the quantity of nicotine per puff, the temperature ofthe puff, the draw, the presence and size distribution of flavorparticles in the puff and like factors are of considerable importance insatisfying habitual smokers. The various alternatives proposed to datehave simply proved unacceptable to most smokers.

To date no device has provided a satisfactory means of adjusting boththe quantity of nicotine delivered in each puff in response to userdemand and/or maintaining adequate precision and accuracy in the dosequantum metered out. Further the devices have failed adequately to mimicthe sensations obtained during smoking.

SUMMARY OF THE INVENTION

An object of the invention is to provide an inhaler.

Another object of the invention is to provide an inhaler that delivers avariety of different medicaments.

Yet another object of the invention is to provide an inhaler thatprovides controlled delivery of a medicament.

Still another object of the invention is to provide an inhaler that canbe substituted for a cigarette.

A further object of the invention is to provide an inhaler that includesa piezoelectric dispenser-head.

A further object of the invention is to provide an inhaler that includesa piezoelectric dispenser-head and an array of dispensing channels.

These and other objects of the invention achieve an inhaler thatdispenses a flowable substance. The inhaler includes an inhaler housingand a mouthpiece coupled to the inhaler housing. A piezoelectricdispenser-head is coupled to the inhaler housing and configured to becoupled to the dispensing chamber. The piezoelectric dispenser-headincludes an array of channels and an array of dispensing nozzles. Thearray of channels are formed with actuatable walls made at leastpartially of a piezoelectric material. Application of an electric fieldto selected side walls reduces a volume in an associated channel andcreates a pressure pulse of flowable substance in the associated channelthrough a dispensing nozzle.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic part sectional perspective view of one embodimentof an inhaler (cigarette substitute) according to the invention; and

FIG. 2(a) is a schematic section in an axial plane of the inhaler ofFIG. 1; and

FIG. 2(b) illustrates in a schematic section another embodiment of theinhaler of FIG. 1 that includes a dispensing head with first and secondsides, first and second dispensing channels, each of which is coupled toa dispensing nozzle;

FIGS. 3A, 3B and 3C are graphs showing the dispensation of an activeingredient (hatched) as a function of inhalation time in use of theembodiment of FIG. 1, and

FIG. 4 is a schematic perspective view of a second embodiment of theinvention, and

FIG. 5 is a schematic diagram of a third embodiment of the invention.

FIG. 6 is a perspective view of a schematically illustratedpiezoelectric dispenser-head.

FIG. 7 is an enlarged partial cross-sectional view of the dispenser-headof FIG. 6 taken along line 7—7 illustrating a parallel channel array ofthe dispenser-head.

DETAILED DESCRIPTION

With reference to FIGS. 1, 2(a) and 2(b) there is shown a firstembodiment of the invention consisting of a dispenser (hereafterreferred to as an “inhaler”) that can include a cigarette-shaped hollowtubular body 1 with connected body parts 2, 3. Body part 2 has a sidewall 4, a mouthpiece 5 at or adjacent one end and a threaded other end6. A plurality of axially extending slots 7 penetrate side wall 4. Bodypart 3 is screw threaded at one end for connection with threaded end 6of body part 2. Body part 3 is closed or constricted at the end 9 remotefrom mouthpiece 5.

Nicotine in a suitable solvent (for example water) or other flowablesubstance is provided in a container 10 which is adapted by means of aspigot shaped outlet and coupling 11, for fluid connection to an inletport 12 of dispenser-head 14. The dispenser head 14 draws flowablesubstance from the inlet port 12 and moves it to the droplet dispensingnozzles 15. In one embodiment, dispenser-head 14 is a piezoelectricdispenser-head 14 with one or more droplet dispensing nozzles 15. Inanother embodiment, dispenser head 14 includes first and second sides14′ and 14″ each with a respective dispensing channel that are coupledto dispensing nozzle 15 (FIG. 2(b)). Dispenser-head 14 is controlled bya controller 16. Suitable controllers include but are not limited toelectronic and microelectronic circuits and sensors, and the like. Inone embodiment dispenser head 14 and controller 16 as well as otherelectrically-powered parts are energized by means of a hollowcylindrical battery 17 via an on-off switch 18 extending through sidewall 4 and operable by the user. When a user inhales at mouthpiece 5, astream of air “A” is drawn into body 1 via slots 7, through body part 2,and mouthpiece 5 into the user's lungs. Slots 7 may be provided with adamper or the like (not illustrated) to control airflow or the devicemay be provided with a porous plug to control airflow (“draw”) oninhalation at mouthpiece 5. A sensor 19 detects a change in pressure orairflow in the device due to inhalation or suction at mouthpiece 5 andissues an actuation signal via cables (not illustrated) to controller16. Controller 16 responds to the actuation signal by issuing an outputsignal or signals via cables (not illustrated) to dispenser-head 14according to pre-programmed parameters or algorithms as hereinafterdescribed. The output or “dose” signal is, or includes, a set of “eject”signals for example a train of voltage pulses. Dispenser-head 14responds to the output signal or signals by issuing a plurality ofdroplets of flowable substance dispensing nozzles 15 of dispenser head14. The flowable substance issues from dispenser-head 14 as a fine sprayof droplets which are entrained in the inhalation airflow from slots 7towards mouthpiece 5. The spray typically comprises fine droplets whichtend to vaporize in the airflow. Optionally, heating means 20 areprovided. In that case the combination of air with droplets may bebrought into thermally conductive contact with heating means 20 prior toleaving mouthpiece 5. This not only produces a sensation on inhalationsimilar to that obtained by smoking a combustible cigarette, but alsoserves to enhance the vaporization of active substance droplets in thegas stream reducing droplet size.

In the embodiment illustrated in FIGS. 1 and 2, the flowable substancecontainer 10 is a collapsible bladder which is housed within aprotective hollow cylindrical cartridge 21 having an air vent 22.However other forms of container (for example a cylinder fitted with apiston) could be used. Cartridge 21 is optional and serves to shieldcontainer 10. Container 10 is disposable or replaceable and may beadapted for fluid communication with inlet port 12 of dispenser-head 14by means of a threaded, bayonet, or other suitably sealing connection.

Optionally, battery 17 may be of annular form and adapted to sleevecartridge 21 to save space. The battery 17 is designed to providesufficient electrical energy to operate the inhaler. When inhaler is notin use there is a saving of energy. Heating means 20 may be infraredheating plates or elements, resistance elements or the like.

Controller 16 desirably comprises a programmable logic circuit forexample a microprocessor together with associated electronic memory,clocks, power supply, sensors and the like and is programmed to controlthe quantity of flowable substance delivered by the inhaler uponinhalation, subject to predetermined criteria.

In normal operation of the inhaler a drop of pressure, or an increase inairflow, at mouthpiece 5 is detected by sensor 19 which issues a signalindicative of inhalation (“actuation” signal) to controller 16 (viacables not illustrated). Controller 16 responds by issuing a “dose”signal to dispenser-head 14 resulting in a spray of droplets from theinhaler.

The “dose” signal typically comprises a predetermined set of droplet“eject” signals which causes one or more dispensing nozzles 15 ofdispenser-head 14 to eject a predetermined number of droplets. The dosesignal may, for example, be a train of pulses (each pulse being adroplet eject signal) directed serially to one of the channels of thedispenser-head 14, or may be a sequence of pulses directed in parallelto a number of channels in the dispenser-head 14. Since the volume of adroplet issued from a selected dispensing nozzles 15 is predeterminedfor a given flowable substance and orifice, and the number of dropletsejected is controlled by the “dose” signal, the total volume of flowablesubstance ejected in response to the “actuation” signal is preciselydetermined.

Controller 16 controls the pulse spacing, pulse width, and pulsefrequency of the “dose” signal as well as the number of pulses ordroplet “eject” signals and therefore determines the time intervalduring which droplets enter the inhalation air stream i.e. the doserate. The number of droplets issued and/or the droplet issue frequencymay be altered by changing data stored in the memory of the controller16. Controller 16 may also be programmed to address specific channels ofthe dispenser-head 14 so as to emit droplets from selected dropletdispensing nozzles 15 which may differ one from another for example inrespect of diameter or orientation.

Controller 16 may also be programmed to provide a time delay betweenreceipt of an “actuation in that the body is of rectangularcross-section and in that of the shape and arrangement of componentsdiffers.

A further difference is that in the embodiment of FIG. 4 the mouthpieceportion 5 is moveable hingedly between a storage position “A” in whichit is in alignment with the body (shown in ghost outline in FIG. 4) andan active position “B” in which it is inclined at an angle to the bodyportion.

The mouthpiece may swivel about a swivel pin and the swivel motion mayitself actuate an on/off switch to energize the controller 16.

If desired the apparatus may be provided with manual actuation (e.g. apush-button switch, not illustrated) instead of a pressure-sensitiveswitch, to control the operation and initiate an “actuation” signal.

In cigarette substitute apparatus according to FIG. 1, droplet sizes ofthe order of 1-20 micron diameter or more are acceptable. For pulmonaryadministration of drugs a small droplet size 1-5 micron diameter ispreferred. For practical purposes droplets of below 10 micron diameterand more preferably of below 5 micron diameter are therefore preferred.If necessary, droplet size can be reduced after ejection from thedispenser-head by directing droplets at each other or at a suitabletarget designed to further fragment the droplets, or by injecting thedroplets into an inhaled stream in a suitable manner. Optionally heatingdevices can be employed to vaporize the flowable substance and reducedroplet size.

Suitable drugs for delivery by the inhaler described include, by way ofexample only, analgesics, peptides and proteins. Other suitable agentsinclude

(i) B₂-bronchodilators—salbutamol, terbutaline sulphate, fenoterolhydrobromide, pirbuterol, reproterol hydrochloride, rimiterolhydrobromide, salmeterol (used extensively for treatment of acute asthmaattacks and in prophylactic asthma therapy).

(ii) Antimuscarinic bronchodilators—Ipratropium bromide, oxitropiumbromide (used in management of chronic bronchitis).

(iii) Corticosteroids—beclomethasone dipropionate, budesonide: used inprophylactic asthma therapy.

(iv) Sodium chromoglycate, nedocromil sodium (used in prophylacticasthma therapy). Antibiotic Therapy:

(v) Pentamidine isethionate—(antibiotic for the prophylaxis andtreatment of pneumonia due to Pneumocystis carinii, a common secondaryinfection in HIV/AIDS patients).

Local Action

(vi) Range of proprietary ‘Over the Counter’ nasal decongestant spraysfor common cold symptoms,

(vii) Corticosteroids—beclomethasone dipropionate, betamethasone sodiumphosphate, budesonide, fluticasone propionate (used in prophylaxis andtreatment of allergic rhinitis).

(viii) Sodium chromoglycate (used in prophylaxis of allergic rhinitis).

(ix) Anti-infective agents—e.g. dexamethasone, fusafungine,chlorhexadine hydrochloride (used in treatment of infection due to nasalstaphylococci).

Systemic Action

(x) Nasal administration of peptides related to antidiuretichormone—desmopressin, lypressin (used in management of diabetesinsipidus).

The apparatus for use in dispensing certain drugs may compriseprogrammed control means which issues a predetermined dose into each ofa plurality of successive inhalations and in that case may be providedwith a “dose complete” signal for example via LED 31 to indicate to auser when a full dose has been dispensed. The dose can be variedaccording to the composition being dispensed and the prescription foreach user.

With reference to FIG. 5, there is shown a further embodiment of theinvention which is adapted to dispense an active substance such as ananaesthetic, antiseptic or a liquid medication by topical applicationrather than by inhalation.

In surgery or medical treatment it is sometimes necessary to apply ananaesthetic, antiseptic or other fluid over a local area by means of anaerosol sprayed from a pressurized container. However it is difficult tocontrol the amount and location of spray application. Moreover the useof CFC propellant as used in the aerosol is environmentally undesirable.

Parts of FIG. 5 corresponding in function to parts in the embodiment ofFIG. 1 are identified by the same numerals.

With reference to FIG. 5 there is shown a dispenser comprising a penshaped hollow tubular body 1 assembled from hollow body parts 2, 3. Bodypart 2 has a nozzle opening 25 at one end while body part 3 is closed atthe end remote from nozzle opening 25. Body parts 2, 3 are separableconnected at 6, for example by inter-engaging thread formations. Acontainer 10 is situated within body 1 and contains a flowablesubstance. Container 10 is in fluid connection with one or moredispenser-heads 14 via one or more conduits. In the present exampledispenser-head 14 is a piezoelectric crystal device such as used in anink jet print head. Dispenser-head 14 can be energized from a battery 17via an “on/off” control switch 18 adapted for finger operation while thedispenser is hand held. For example the dispenser may be held betweenthumb and middle finger and may carry a push button switch 18 which isoperable by the first finger. In the embodiment of FIG. 5 when controlswitch 18 is actuated, dispenser-head 14 delivers flowable substancefrom container 10 through dispensing nozzles 15 as a spray of dropletsdirected outwardly from the dispenser via nozzle opening 25. Theduration of the spray of droplets is determined by whether the controlswitch 18 is “on” or “off”.

In a more highly preferred embodiment of the invention the volume offlowable substance sprayed as droplets per unit time can also becontrolled. For example, the dispenser 1 is provided with one or moreswitches 26 (for example touch pad switches) which condition controller16 (for example a microprocessor circuit) which in turn controls theamount of flowable substance being dispensed through dispensing nozzles15 of dispenser-head 14 from which droplets are emitted and/or whichcontrols the repetition rate of the dispenser-head 14 and thus thenumber of droplets delivered in a unit of time. Thus the droplet sprayrate may be selectively light or heavy depending on the number ofdispensing nozzles 15 emitting droplets and depending on the repetitionrate of droplet emission.

If the dispenser-head 14 is provided with a plurality of dispensingnozzles 15 which are directed at preselected angles to the axis of thebody, droplets of flowable substance may be directed in the axialdirection or selectively at predetermined angles to the axial directionby controller actuation of a selected dispensing nozzle 15, or aselected combination of dispensing nozzles 15. In this manner a spraypattern of droplets may be selected by means of a suitable fingercontrol of one or a number of switches 26 forming part of themicroelectronic circuit of controller 16. If all dispensing nozzles 15are directed axially the spray pattern may be made selectively narrow orbroad.

Alternatively switches 26 may be adapted to select between a number ofpredetermined total dose dispensations or an additional controller maybe provided to select total dose. In such manner, if the dispensercontains for example a liquid local anaesthetic, a surgeon can select apreset quantity and spray pattern of local anaesthetic to be appliedduring surgery. The surgeon could thus select between application of asmall, medium or large dose, at each actuation of a switch 26 and couldpreselect between a narrow, medium, or broad spray pattern.

If desired the controller 16 may be provided with means to preventinadvertent excessive use, for example by limiting the maximum dose ofdispensed flowable substance which can be applied within a pre-specifiedtime period.

Also, if desired, the control circuit can be provided with securitylocking which overrides the “on/off” switch. For example the devicemight be provided with a programmable security code and might beincapable of issuing its contents unless and until a corresponding codeis entered by an intending user.

For this purpose the device may have a plug 28, socket or electronictransmitter/receiver which permits the device to interface with anexternal computer. The external computer might then also record dataindicative of use, doses issued, user identification, patientidentification, or similar data. The external computer may also re-enternew data in one or more memories in the controller of the device forexample dose values, time parameters, security codes. This data is thenused in controlling response of the device to actuation by the user.

Other forms of hand control, for example touch sensitive switches orrotary switches may be employed instead of switches 26.

Controller 16 may utilize digital or analogue control and may employ amicroprocessor, or discrete circuit components. In preferred embodimentsthe circuit includes electronic memory, preferably of a type which isnot erased due to lack of battery power. The circuit further desirablyincludes a display screen such as a single line LCD 27. The circuit mayalso employ a clock and be able to utilize and display date and timedata and may have a key pad or equivalent input device or may rely forinput upon communication with an external key pad. The LCD could be usedto display data such as number of remaining doses or time and date oflast dose.

Although the embodiment of FIG. 5 has been described with reference todispensation of a flowable substance it will be appreciated that thematerial to be dispensed can be in the form of a gel, colloid, powdersuspension or any other form suitable for dispensation via thedispenser-head 14.

In a further embodiment of the invention (not illustrated) the dispenserhead is provided with a plurality of cartridges or chambers each adaptedto contain a respective medication in flowable substance or solutionform. Controller 16 may be programmed to provide an alarm (for example abeeper or flashing LED) at predetermined times or at predetermined timesand dates. On next actuation of the device, it then delivers apredetermined dose of one medication or a combination or succession ofmedications each in a respective predetermined dose.

This embodiment is thus ideally suited for pre-programmed treatment ofpersons suffering from dementia or the like and for persons having totake a number of different medications each according to a schedule andwho find self-administration confusing.

The device itself prompts the user to accept a dose and issues theappropriate doses of prescribed medication.

As will be apparent to those skilled in the art, features described inrelation to one of the described embodiments may be combined with thoseof another.

Although the control signals have been described as pulses, thoseskilled in the art will appreciate that the signals can take a greatvariety of forms and may employ voltage or current signals, AC or DCsignals, digital or analogue signals or the like, as required foroperation of the dispenser-head selected. It is not necessary literallyto count signals to eject a predetermined number of droplets and it willbe understood that such expediencies as issuing “eject” signals at apredetermined frequency for a selected time interval are consideredequivalent and within the scope hereof. Although the invention has beendescribed in terms of electronic devices, fluidic devices and nonelectronic means of control may be employed.

Those skilled in the art will appreciate that with many dispenser-headsa principal ejected droplet sometimes has trailing satellite dropletswhich are very much smaller. References herein to a predetermined numberof droplets refer to the number of principal droplets ejected, but ifnecessary the dispenser-head can be calibrated to issue a desired dosetaking account of satellite drops without departing from the inventiveconcept hereof. Likewise it will be understood that the control offlowable substance viscosity is important and that therefore the volumeof one substance issued in response to a given set of “eject” signalswill not necessarily be the same as for another substance. However thoseskilled in the art will have no difficulty based on the teaching hereofin programming devices according to the invention to take account ofthese factors.

In another embodiment of the invention, a drop-on-demand typedispenser-head is employed that utilizes the distortion of apiezoelectric material to eject flowable substance and includes an arrayof channels in which the individual channels of the array each have sidewalls formed at least, in part, of a piezoelectric material. Thechannels are micron sized and are arranged such that the spacing betweenadjacent channels is relatively small. In the operation of this type ofdispenser-head, flowable substance is directed to and resides in thechannels until selectively ejected therefrom. Ejection of flowablesubstance from selected channels is effected due to theelectromechanical nature of the piezoelectric side walls of thechannels. Because piezoelectric material deforms when an electric fieldis applied there across, the side walls of selective channels deform byapplying an electric field across select ones thereof. The electricfield may be so selectively applied by digital or other means. Thisdeformation of side walls of selected channels reduces the volume of therespective channels creating a pressure pulse in the flowable substanceresiding in those channels. The resultant pressure pulse then causes theejection of a droplet of flowable substance from the front end of theparticular channel adjacent the side walls across which the electricfield is applied. The channels provide a correct delivery volume that isdifficult to achieve in a single channel. Additionally, multiplechannels give access to more volume of flowable substance in a shorterperiod of time.

As shown in FIG. 6, the dispenser-head 110 includes a main body portion112 which is aligned, mated and bonded to an intermediate body portion114 which, in turn, is aligned, mated and bonded to a top body portion116.

A plurality of vertical grooves of predetermined width and depth areformed through the intermediate body portion 114 and the main bodyportion 112 to form a plurality of pressure chambers or channels 118(not visible in FIG. 6), thereby providing a channel array forming thedispenser-head 110. In conventional manner, channels 118 are in fluidconnection to an inlet port 160 and fluid container 162.

The dispenser-lead 110 further includes a front wall 120 having aplurality of dispensing nozzles 122 extending therethrough. Eachdispensing nozzle 122 is in fluid connection with a corresponding one ofthe plurality of channels 118, thereby providing droplet dispensingnozzles for dispenser-head 110.

FIG. 7 shows an enlarged partial cross-sectional view of dispenser-head.110 taken along line 7—7 of FIG. 6. Dispenser-head 110 includes aplurality of parallel spaced channels 118. Each channel 118 extendsvertically from top body portion 116, along intermediate body portion114 and part of main body portion 112 and extends lengthwise throughdispenser-head 110. Main body portion 112 may be constructed of inactiveor active material such as unpolarized or poled piezoelectric material.Top body portion 116 may be constructed of an inactive material such asunpolarized piezoelectric material.

Separating adjacent channels 118 are sidewall actuators 124, each ofwhich include a first sidewall section 126 and a second sidewall section128. First sidewall section 126 may be constructed of an inactive oractive material such as for an unpolarized or poled piezoelectricmaterial. In one embodiment, first sidewall section 126 is integrallyformed with body portion 112. When first sidewall section 126 isconstructed of an active poled piezoelectric material, it may be formedof lead zirconate titanate (PZT), polarized in direction “P”perpendicular to channels 118. Second sidewall section 128, is formed ofan active material such as lead zirconate titanate (PZT) and polarizedin direction “P” perpendicular to channels 118.

Mounted to the top side of each first sidewall section 126 is ametallized conductive surface 130 which can be a strip of metal.Similarly, metallized conductive surfaces 132 and 134, also formed of astrip of metal, are mounted to the top and bottom sides, respectively,of each second sidewall section 128. A first layer of a conductiveadhesive 136 is provided to conductively attach metallized conductivesurface 130, mounted to first sidewall section 126, and metallizedconductive surface 134, mounted to second sidewall section 128.Conductive adhesive 136 can be an epoxy. Finally, the bottom side of topbody portion 116 is provided with a metallized conductive surface 138.Metallized conductive surface 138 is mounted to metallized conductivesurface 132 of second sidewall section 128 by a second layer of aconductive adhesive 140. In this manner, a series of channels 118, eachchannel being defined by the piezoelectric material of main body portion112 along its bottom, the layer of conductive adhesive 140 along its topand a pair of sidewall actuators 124 is provided. Each sidewall actuator124 is shared between adjacent channels 118.

A passivation coating may be applied to all exposed metallizedconductive surfaces. In one embodiment, the metallized surfaces indispenser-head 110 are electropolished prior to the deposition ofpassivation coatings. Dispenser-head 110 is placed in an acid bath and avoltage supply is attached to dispenser-head 110 in a manner to make theexposed metallized surfaces into the anode. When the voltage supply isenergized, a slight amount of the metal of the metallized surfaces, suchas surfaces 130 and 134, is removed or etched at the fluid interfacewhich does not degrade the performance of dispenser-head 110. Thisminimizes the amount of exposed metal to be coated by the passivationcoatings.

In an embodiment referring to FIG. 6, front wall 120 is a porousmembrane and droplets may be created by forcing a flowable substancethrough the pores of the porous membrane. In a further embodiment theporous membrane is positioned adjacent to the dispensing nozzles 122 ofdispenser-heads 110. Membrane 120 has pores of sufficient size and insufficient numbers such that when the flowable substance is forcedagainst membrane 120 by the dispenser-head 110 the flowable substance isaerosolized and droplets suitable for inhalation are created. In oneembodiment, membrane pores have a size in the range of about 0.25 to 2.5microns. When the pores have this size the particles which escapethrough the pores to create the aerosol have a diameter in the range of0.5 to 5 microns.

Droplets may be released with an air flow intended to keep the particleswithin this size range. The creation of small particles may befacilitated by the use of a vibration device such as the piezoelectricdispenser-head described in FIG. 6, which provides a vibration frequencyin the range of about 800 to about 4000 kilohertz. Those skilled in theart will recognize that some adjustments can be made in the parameterssuch as the size of the pores from which fluidic medium is released,vibration frequency, pressure, and other parameters based on the densityand viscosity of the formulation to be aerosolized particles having adiameter in the range of about 0.5 to 20 microns.

Membrane 120 may include pores which have a diameter in the range ofabout 0.25 micron to about 6 microns and a pore density in the range of1×10 sup 4 to about 1×10 sup 8 pores per square centimeter. Membrane 120may be made of material having a density in the range of about 0.25 to3.0 mg/cm², more preferably about 1.7 mg/cm sup 2, and with a thicknessof about 2 to about 20 microns, more preferably 8 to 12 microns.Alternatively, membrane 120 can be an area of pores with a diameter inthe range of 0.25 micron to about 6 microns; which pores are positionedover the area of about 1 sq. mm. to about 1 sq. cm.; and which areacontains from 10 to 10,000 pores.

The material of the membrane has sufficient structural integrity so thatit is maintained intact (will not rupture) when the material issubjected to force sufficient to aerosolize the flowable substance. Thatforce can be in range of 20 to about 200 psi while flowable substance isforced through the pores of membrane 14.

Membrane 120 can be made of a hydrophobic material including but notlimited to polycarbonates, polyesters, and the like, with the poresbeing formed by anisotropic etching, etching through a thin film, andthe like. The membrane material can include pores of different geometricconfigurations including but not limited to cylinders, non-cylinders,spherical, non-spherical, hour-glass, conical, square, rectangular andirregular shapes. When a conical configuration is used it is designedwith the narrowest point of the conical configuration having an openingwith a diameter in the range of 0.2 micron to 6 microns.

The foregoing description of a preferred embodiment of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. Obviously, many modifications and variations will be apparentto practitioners skilled in this art. It is intended that the scope ofthe invention be defined by the following claims and their equivalents.

What is claimed is:
 1. An inhaler, comprising: an inhaler housing; amouthpiece interconnected with said inhaler housing; a flowablesubstance container associated with said inhaler housing; a dropletejection device fluidly interconnected with said flowable substancecontainer, wherein said droplet ejection device comprises a plurality ofdroplet ejection orifices and a plurality of droplet ejection actuatorswhich are independently actuatable; a programmable controlleroperatively interconnected with said droplet ejection device; and aheating means disposed within said inhaler housing.
 2. An inhaler, asclaimed in claim 1, wherein: said inhaler housing comprises first andsecond ends, wherein said mouthpiece is disposed on said first endwherein said second end is closed.
 3. An inhaler, as claimed in claim 1,wherein: said inhaler housing comprises a plurality of air inlet slots.4. An inhaler, as claimed in claim 3, wherein: said inhaler housingcomprises first and second ends and a sidewall extending therebetween,wherein said air inlet slots are disposed on said sidewall.
 5. Aninhaler, as claimed in claim 3, wherein: said inhaler housing comprisesa central, longitudinal axis, wherein said air inlet slots are disposedparallel to said central, longitudinal axis.
 6. An inhaler, as claimedin claim 3, further comprising: means for controlling airflow throughsaid air inlet slots.
 7. An inhaler, as claimed in claim 1, wherein:said inhaler housing comprises first and second ends with a sidewallextending therebetween, wherein said mouthpiece is disposed on saidfirst end and defines an exit from said inhaler housing, wherein saidsecond end is closed, and wherein said inhaler housing comprises aplurality of air inlet slots disposed on said sidewall and which definean inlet to said inhaler housing.
 8. An inhaler, as claimed in claim 1,wherein: said inhaler housing comprises first and second housingsections which are detachably interconnected, wherein said flowablesubstance container is disposed within said inhaler housing and may beaccessed by separating said first housing from said second housing. 9.An inhaler, as claimed in claim 1, wherein: said flowable substancecontainer comprises a protective cartridge and a collapsible bladderdisposed within said protective cartridge.
 10. An inhaler, as claimed inclaim 1, wherein: said flowable substance container is disposable andmay be replaced by another said flowable substance container.
 11. Aninhaler, as claimed in claim 1, wherein: said flowable substancecontainer is disposed within said inhaler housing.
 12. An inhaler, asclaimed in claim 1, wherein: at least some of said plurality of dropletejection orifices have different diameters.
 13. An inhaler, as claimedin claim 1, wherein: at least some of said plurality of droplet ejectionorifices are disposed in different orientations.
 14. An inhaler, asclaimed in claim 1, wherein: said heating means is disposed between saiddroplet ejection device and said mouthpiece.
 15. An inhaler, as claimedin claim 1, wherein: said heating means comprises means for increasing atemperature of droplets ejected from said droplet ejection device. 16.An inhaler, as claimed in claim 1, wherein: said heating means comprisesmeans for reducing a size of droplets ejected from said droplet ejectiondevice.
 17. An inhaler, as claimed in claim 1, wherein: said controllercomprises a programmable logic circuit.
 18. An inhaler, as claimed inclaim 1, wherein: said controller comprises a microprocessor.
 19. Aninhaler, as claimed in claim 1, wherein: said controller comprises meansfor controlling a quantity of a flowable substance ejected from saidflowable substance container by said droplet ejection device.
 20. Aninhaler, as claimed in claim 1, further comprising: an inhalation sensorassociated with said inhaler housing and operatively interconnected withsaid controller.
 21. An inhaler, as claimed in claim 1, wherein: saidcontroller comprises means for sending a dose signal to said dropletejection device.
 22. An inhaler, as claimed in claim 21, wherein: saiddose signal comprises a set of eject signals.
 23. An inhaler, as claimedin claim 21, wherein: said dose signal comprises a train of voltagepulses.
 24. An inhaler, as claimed in claim 21, wherein: said dosesignal comprises a train of pulses directed serially to one of saiddroplet ejection actuators.
 25. An inhaler, as claimed in claim 21,wherein: said dose signal comprises a sequence of pulses directed inparallel to a plurality of said droplet ejection actuators.
 26. Aninhaler, as claimed in claim 1, wherein: said controller comprises meansfor programming said controller to address specific said dropletejection actuators so as to eject droplets of a flowable substance fromselected said droplet ejection orifices.
 27. An inhaler, as claimed inclaim 1, wherein: said controller comprises means for controlling apulse spacing, pulse width, and pulse frequency of a dose signal sent tosaid droplet ejection device by said controller.
 28. An inhaler, asclaimed in claim 1, wherein: said controller comprises means forcontrolling a time interval during which droplets of a flowablesubstance are discharged from said droplet ejection device.
 29. Aninhaler, as claimed in claim 1, wherein: said controller comprises meansfor providing a dose complete signal which indicates to a user of saidinhaler that a full dose has been dispensed.
 30. An inhaler, as claimedin claim 1, wherein: said controller comprises means for preventinginadvertent, excessive use of said inhaler.
 31. An inhaler, as claimedin claim 1, wherein: said controller comprises means for limiting amaximum dose of a flowable substance from said flowable substancecontainer which can be discharged from said inhaler within apredetermined time period.
 32. An inhaler, as claimed in claim 1,wherein: said controller comprises means for locking said inhaler. 33.An inhaler as claimed in claim 32, wherein: said means for lockingcomprises a security code.
 34. An inhaler, as claimed in claim 1,wherein: said controller comprises means for providing an alarm schedulewhereby an alarm will be activated in accordance with said alarmschedule.
 35. An inhaler, as claimed in claim 1, wherein: saidcontroller comprises a microprocessor, electronic memory, clocks, powersupply, and sensors.
 36. An inhaler, as claimed in claim 1, furthercomprising: a battery operatively interconnected with said controller.37. An inhaler, as claimed in claim 36, wherein: said battery isdisposed within said inhaler housing.
 38. A method for deliveringdroplets of a flowable substance from an inhaler to a patient, whereinsaid inhaler comprises a controller which is operatively interconnectedwith a droplet ejection device, wherein said droplet ejection devicecomprises a plurality of droplet ejection orifices and a plurality ofdroplet ejection actuators, and wherein said method comprises the stepsof: providing said flowable substance to said droplet ejection device;executing a first programming step which comprises programming acontroller which is operatively interconnected with said dropletejection device, wherein said programming step comprises selecting whichof said droplet ejection actuators should receive a first dose signalfrom said controller; directing said first dose signal to each of saiddroplet ejection actuators from said selecting step; discharging saidflowable substance through said droplet ejection orifices associatedwith said droplet ejection actuators from said selecting step;generating droplets of said flowable substance from said dischargingstep; and inhaling said droplets provided by said generating step.
 39. Amethod, as claimed in claim 38, wherein: said executing a firstprogramming step comprises operatively interconnecting said inhaler withan external computer.
 40. A method, as claimed in claim 38, furthercomprising the steps of: executing a second programming step comprisingprogramming said controller which is operatively interconnected withsaid droplet ejection device and which comprises selecting which of saiddroplet ejection actuators should receive a second dose signal from saidcontroller, wherein a combination of said droplet ejection actuatorsfrom said selecting step of said executing a first programming step aredifferent from a combination of said droplet ejection actuators fromsaid selecting step of said executing a second programming step.
 41. Amethod, as claimed in claim 38, wherein: said selecting step comprisesselecting a single said droplet ejection actuator to receive said firstdose signal from said controller.
 42. A method, as claimed in claim 38,wherein: said directing step comprises directing a set of ejectionsignals.
 43. A method, as claimed in claim 38, wherein: said directingstep comprises directing a train of voltage pulses.
 44. A method, asclaimed in claim 38, wherein: said directing step comprises directing atrain of pulses serially to one of said droplet ejection actuators. 45.A method, as claimed in claim 38, wherein: said directing step comprisesdirecting a sequence of pulses in parallel to a plurality of saiddroplet ejection actuators.
 46. A method, as claimed in claim 38,wherein: said directing step comprises directing a sequence of pulses,wherein said programming step comprises programming a pulse spacing, apulse width, and pulse frequency of said sequence of pulses.
 47. Amethod, as claimed in claim 38, further comprising the step of: heatingsaid droplets after said generating step and before said inhaling step.48. A method, as claimed in claim 47, wherein: said heating stepcomprises affecting a temperature of said droplets.
 49. A method, asclaimed in claim 47, wherein: said heating step comprises reducing asize of said droplets.
 50. A method, as claimed in claim 38, furthercomprising the step of: providing a resistance to said inhaling step.51. A method, as claimed in claim 38, further comprising the step of:providing a dose complete signal to said patient after a full dose hasbeen dispensed from said inhaler.